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Konrad Mollenhauer, Uni Kassel - h-a-d.hr . Konrad Mollenhauer_Razlicite tehnologije... · PDF filematerial (in situ or in plant) • Bituminous binder (bitumen emulsion or foamed

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Text of Konrad Mollenhauer, Uni Kassel - h-a-d.hr . Konrad Mollenhauer_Razlicite...

  • Hrvatsko asfaltersko drutvo Croatian asphalt association

    Raziliite tehonologije hladnog in-situ recikliranja u Europi i orgranienja uvjetovana

    stanjima cesteVariety of cold-in-place recycling technologies

    within Europe and limits regarding varyingroad conditions

    Konrad Mollenhauer, Uni Kassel

    Meunarodni seminar ASFALTNI KOLNICI 2017International seminar ASPHALT PAVEMENTS 2017

    Opatija, 05. 06. 04. 2017.

  • Cold recycling mixtures vary considerable in

    Europe

    Binder types

    Bitumen emulsion

    Foamed bitumen

    Cement

    Binder contents

    Mix design procedures

    Laboratory Compaction methods

    Accelerated Curing procedures

    Mechanical test methods

    Specification values

    Project aim: Prepare harmonisation process

    Cold Recycling Technologies in Europe: CoRePaSol-Project

    Characterization of advanced cold

    recycled bitumen stabilized

    pavement solutions

    Project funded by CEDR

    2013-2014

    Kolnici 2017 | Asphalt Pavements 2017 | Konrad Mollenhauer | 06.04.2017 | Opatija | 2

  • Cold Recycling-Technologies in Europe

    Construction procedure

    Variety of mix concepts

    Effect of mix composition

    Proposal for mix design

    Limits regarding varying road conditions

    Results of laboratory project

    Recommendations

    Content of presentation

    Asphaltni Kolnici 2017 | Asphalt Pavements 2017 | Konrad Mollenhauer | 06.04.2017 | Opatija | 3

  • Cold Recycling: Mix and constrcution procedures

    1. Milling / Granulation of existing

    pavement

    2. Mixing crushed pavement

    material (in situ or in plant)

    Bituminous binder (bitumenemulsion or foamed bitumen)

    Cement (mineral binder oractive filler)

    Additional aggregates toadjust grading

    3. Paving

    4. Compaction

    5. Construction of surface layer(s)

    Asphaltni Kolnici 2017 | Asphalt Pavements 2017 | Konrad Mollenhauer | 06.04.2017 | Opatija | 4

    Mixing and compaction at ambient temperatures require addition of water

    Water results in high voids content and reduced bearing capacity after construction and

    has to be removed from the layer:

    Evaporation/Drainage in warm climate Addition of cement in moist climate

  • Cold recycled road materials: Variety of mixes

    Asphaltni Kolnici 2017 | Asphalt Pavements 2017 | Konrad Mollenhauer | 06.04.2017 | Opatija | 5

    Collings et al., 2009

  • Cold recycled road materials: Variety of mixes

    Type and degree of bonding

    affects:

    Visco-ealsticity / stiffness

    Curing time

    Cracking / rutting resistance

    Water sensitivity

    Asphaltni Kolnici 2017 | Asphalt Pavements 2017 | Konrad Mollenhauer | 06.04.2017 | Opatija | 6

  • 1. Pre-assessment of mix granulate

    Continuous grading (concrete type)

    Assessment of optimum moisture content (mod. Proctor)

    2. Selection of binder content range

    BSM for dry climate or soft subground (only with foamed bitumen)

    CBSM for moist climate

    3. Compaction of specimens for mechanical tests

    4. Laboratory curing

    BSM: 3 days oven drying @ 50 C

    CBSM: 28 days at room conditions

    5. Specimen assessment

    Void content (the lower the better)

    Stiffness

    Strength (e. g. Indirect tensile tests - ITS)

    both properties: higher values are better however, not to be reached by excess addition of cement

    CoRePaSol: Proposed (harmonised) mix design procedure

    Asphaltni Kolnici 2017 | Asphalt Pavements 2017 | Konrad Mollenhauer | 06.04.2017 | Opatija | 7

    60 60

    d0

    d0

    d60d60

  • Homogeneity of reclaimed asphalt is a

    predominating property controlling the hot

    recycling process

    Nomograms for allowed RA contents are available

    RA content results of homogeneity of RA properties and allowed tolerances within mix composition (binder content, grading, )

    For cold recycling, effects of non-homogeneious

    pavements are not known

    Changing structural properties are obstancles for

    Cold recycling (especially: cold-in-place)

    Research question (within CoRePaSol-project):

    What are the limits of homogeneities for cold recycling process?

    What is the effect of (aged) bitumen in recycled asphalt within cold recycling mixtures?

    Limits for varying pavement conditions for cold recycling

    Asphaltni Kolnici 2017 | Asphalt Pavements 2017 | Konrad Mollenhauer | 06.04.2017 | Opatija | 8

  • Limits for varying pavement conditions for cold recycling

    Asphaltni Kolnici 2017 | Asphalt Pavements 2017 | Konrad Mollenhauer | 06.04.2017 | Opatija | 9

    Conditions of pavement to be

    rehabilitated can vary

    grown road with multiple maintenances during last centuries/decades

    Road widening on one side

    Small repair sections

    Varying parameters:

    Layers (materials)

    Thickness

    Conditions

    In given milling horizon:

    Asphalt layers

    Hydraulically bound layers

    Unbound layers

    Transversal and longitudinal

    differences

    0

    10

    20

    30

    40

    50

    60

    70

    80

    Pav

    emen

    t d

    epth

    [cm

    ]

    SMA AC B AC T Cement Base Unbound Subbase

    0

    10

    20

    30

    40

    50

    60

    70

    80

    Pav

    emen

    t d

    epth

    [cm

    ]

    BSM Unbound Subbase

  • Reclaimed asphalt 0/16

    Binder content: 5.4 %,

    TR&B: 63.5C,

    Pen 23 1/10 mm

    Reclaimed road concrete 0/22

    Basaltic aggregates (to simulate reclaimed

    unbound base)

    Mix design (BCSM):

    Addition of 3,6 % limestone filler to adjust grading

    4 % added bitumen content

    a) Foamed bitumen 50/70

    b) Bitumen emulsion

    2 % cement

    Moisture content: 7,8 %

    Laboratory study: Effect of mix granulate composition on cold recycled material

    Asphaltni Kolnici 2017 | Asphalt Pavements 2017 | Konrad Mollenhauer | 06.04.2017 | Opatija | 10

    0

    10

    20

    30

    40

    50

    60

    70

    80

    90

    100

    0,0

    62

    5

    0,1

    25

    0,2

    5

    0,5 1 2 4 8 16

    32

    pa

    ssin

    g [%

    ]sieve [mm]

    Mix designReclaimed asphaltReclaimed road concrete

  • Selection of mix variations

    Asphaltni Kolnici 2017 | Asphalt Pavements 2017 | Konrad Mollenhauer | 06.04.2017 | Opatija | 11

    100 %

    reclaimed

    asphalt

    Reclaimed

    asphalt +

    unbound base

    Reclaimed

    asphalt +

    reclaimed road

    concrete

    Reclaimed

    asphalt +

    reclaimed road

    concrete +

    unbound base

  • Mix

    variations

    Reclaimed

    asphalt

    (RA)

    Reclaimed

    road

    concrete

    (RRC)

    Unbound

    material

    (unb.)

    A 100/0/0 96,4 - 3,6

    B 75/0/25 77,1 22,9

    C 50/25/25 48,2 25,0 26,8

    D 50/0/50 48,2 - 51,8

    E 40/20/40 38,6 20,0 41,4

    F 0/50/50 - 50,0 50,0

    G 0/25/75 25,0 75,0

    H 0/0/100 - - 100,0

    Laboratory study: Effect of mix granulate composition on cold recycled material

    Asphaltni Kolnici 2017 | Asphalt Pavements 2017 | Konrad Mollenhauer | 06.04.2017 | Opatija | 12

    0% 50% 100%

    A 100/0/0

    B 75/0/25

    C 50/25/25

    D 50/0/50

    E 40/20/40

    F 0/50/50

    G 0/25/75

    H 0/0/100

    Mix granulate compositions

    Reclaimed asphalt

    Reclaimed road concrete

    Unbound Aggregates

  • Cold recycling mix composition and test program

    Asphaltni Kolnici 2017 | Asphalt Pavements 2017 | Konrad Mollenhauer | 06.04.2017 | Opatija | Nr.

    Test program:

    Static compaction (30 s 45.9 kN)

    Specimen curing:

    1 day in mould

    2 days in mould (~ 20 C)

    25 days at room conditions

    Tests

    Bulk density & void content

    Indirect tensile strength (5 C)

    Water sensitivity (ITS dry vs. 14 days in water)

    CBRdry (California Bearing Ratio)

    Mix preparation

    Specimen curingITS CBR

  • Results: Void content after 28 days of (dry) curing at room conditions

    Comparably high void contents

    Low compaction energy (lowercompared to field compaction)

    Coarse mix with low finescontent

    Mixtures containing RA are

    better to compact compared to

    mixtures without RA

    Little effect of reclaimed road

    concrete vs. unbound

    aggregates

    Similar void content for

    emulsion and foamed bitumen

    mixtures

    Asphaltni Kolnici 2017 | Asphalt Pavements 2017 | Konrad Mollenhauer | 06.04.2017 | Opatija | 14

    0,0

    5,0

    10,0

    15,0

    20,0

    25,0

    30,0

    A B C D E F G H

    100%75% 50% 50% 40% - - -

    - - 25% - 20% 50% 25% -

    - 25% 25% 50% 40% 50% 75%100%

    Vo

    ids c

    on

    ten

    t V

    28

    [%]

    Bitumen emulsion

    Foamed bitumen

    Sample

    RA

    RRC

    unb.

  • Results: Indirect tensile strength ITSdry after 28 days of curing (5 C)

    Asphaltni Kolnici 2017 | Asphalt Pavements 2017 | Konrad Mollenhauer | 06.04.2017 | Opatija | 15

    Foamed bitumen

    Bitumen emulsion

    0,0

    0,2

    0,4

    0,6

    0,8

    1,0

    1,2

    1,4

    1,6

    A B C D E F G H

    100%75% 50% 50% 40% - - -

    - - 25% - 20% 50% 25% -

    - 25% 25% 50% 40% 50% 75%100%

    Ind

    irect

    ten

    sile s

    tren

    gth

    IT

    Sd

    ry(5C

    ) [M

    Pa]